Partial Design Process These resources engage students in some of the steps in the engineering design process,
but do not have them complete the full process. While some of these resources may focus heavily on the brainstorm and design steps,
others may emphasize the testing and analysis phases.

Hands-on Activity:Leaning Tower of Pasta

Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Summary

Using spaghetti and marshmallows, students experiment with different structures to determine which ones are able to handle the greatest amount of load. Their experiments help them to further understand the effects that compression and tension forces have with respect to the strength of structures. Spaghetti cannot hold much tension or compression; therefore, it breaks very easily. Marshmallows handle compression well, but do not hold up to tension.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Students investigate compression and tension forces and examine their affect on the strength of structures

Engineering Connection

Engineers consider tension and compression forces when designing a building or structure, and choosing the materials to build it. All structures must be able to handle the forces that act upon them so they will not fail and injure people, wildlife or the environment. Like all structures, the foundation, frame and joints of a skyscraper must be able to withstand enormous tension and compression forces — from the weight of its own materials, the load of people and equipment it holds and the impact of natural forces such as wind, snow and earthquakes.

Learning Objectives

After this activity, students should be able to:

Understand that compression and tension affect the stability of a structure

Compare their model to others to understand why some models are stronger than others

Use number sense to correlate the strength of a structure to the amount of weight it holds

Understand why engineers consider tension and compression forces when designing and choosing the appropriate materials for a building or structure

More Curriculum Like This

Strong as the Weakest Link

To introduce the two types of stress that materials undergo — compression and tension — students examine compressive and tensile forces and learn about bridges and skyscrapers. They construct their own building structure using marshmallows and spaghetti to see which structure can hold the most weigh...

Students are presented with a brief history of bridges as they learn about the three main bridge types: beam, arch and suspension. They are introduced to two natural forces — tension and compression — common to all bridges and structures.

Students learn about the types of possible loads, how to calculate ultimate load combinations, and investigate the different sizes for the beams (girders) and columns (piers) of simple bridge design. Additionally, they learn the steps that engineers use to design bridges.

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics;
within type by subtype, then by grade, etc.

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(Grades 6 - 8)
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Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
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Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association, and nonlinear association.
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Solve real-world and mathematical problems involving the four operations with rational numbers.
(Grade 7)
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Formulate, represent, and use algorithms with rational numbers flexibly, accurately, and efficiently.
(Grade 7)
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Materials List

Each group needs:

20 unbroken pieces of uncooked, long pasta, such as spaghetti, linguine or fettuccini

30 small marshmallows

Measuring tape or ruler

Weights or small books

Introduction/Motivation

Have you ever wondered how really tall buildings stay up? Why do sky scrapers not fall down when wind hits them? Engineers work with architects and scientists to understand what makes materials break, and then use what they learn to design strong structures. Today, you will have the opportunity to figure out how to make a strong structure, too. Sometimes, engineers may be able to find very strong materials, but they cannot use them in a structure because the material are too expensive. Sometimes, engineers cannot use as much material as they might like due to budget or supply limitations. Just like an engineer, today you will be constrained; you can only use a limited amount of materials. Your job is to design and build a structure that is as tall and strong as possible, using only marshmallows and spaghetti.

As you build, think about what forces will be acting upon your structure. Which parts will be pushed together — that is, which will experience compression — and which parts will be pulled apart — that is, which will be under tension. Is it better to have a piece of spaghetti or a marshmallow under tension? Under compression? How will you design the tallest, strongest structure using limited resources?

The object of this activity is to build a tower as high AND as strong as you can using only a limited supply of spaghetti (or linguine or fettuccini) and marshmallows. There are no step-by-step instructions for this project, only the constraints of limited resources! Students can do whatever they want with the materials to try to build a structure as tall, stable and strong as possible. The project can be made more difficult by adding more constraints such as fewer materials, a minimum height requirement, or a requirement to support at least a minimum weight for a given time. Let the student teams' imagination, creativity and ingenuity run wild.

Hold a competition and give points for how tall the structure is as well as how much weight it can hold. A good way to comparatively measure the effectiveness of each structure is by having students take the load the structure can support and divide it by the weight of the structure. The higher this number, the more effective the structure. For example, 30g (maximum weight structure could hold) divided by 10g (weight of structure alone) = 3.

Before testing the structures (see Figure 1), have students measure and record the height and weight of their structure.

How much weight does the structure support? Five grams? 10 grams? 20 grams? 30 grams? Have students record their structure's maximum weight held on the worksheet, and calculate the load to weight ratio for comparison purposes.

As a class, graph the amount of weight each structure held vs. how much each structure weighed as well as the height of the structure. Discuss different trends and use the graph to lead in to the other discussion questions.

After the competition, hold a class discussion:

- Discuss which structure was the tallest and held the most weight. Which structures had the highest ratio of load to structure weight? Which structures held the most weight, regardless of height, and why.

- Discuss the success or failure of the materials used. Spaghetti cannot hold much tension or compression; therefore, it breaks very easily. Marshmallows handle compression well, but do not hold up to tension (the spaghetti can slip out of them).

Attachments

Safety Issues

The rigid, long pasta could injure an eye. Although this is an activity with a lot of freedom, students should not horseplay with the spaghetti.

Troubleshooting Tips

Before students start construction, be sure they understand where you will add weight to their structure to test it. Knowing this should be a consideration in their structure design. For example, it is difficult to add weight to a tall, narrow tower.

Assessment

Have you ever built a tower? What did you use for the material(s)? How strong was it? How did you know it was/was not strong?

Activity Embedded Assessment

Worksheet: Have the students complete the activity worksheet; review their answers to gauge their mastery of the subject.

Pairs Check: After student teams finish their worksheets, have them compare answers with a peer group, giving all students time to finish the worksheet.

Post-Activity Assessment

Class Presentations: Have the student groups take turns presenting the structures to the rest of the class. Ask them to explain where the forces tension and compression are taking place. Have the class determine which shapes seem to be the strongest for holding up weight.

Toss-a-Question: Using questions 1-7 on the Standing Strong Worksheet, have students work in groups and toss a ball (or wad of paper) back and forth. The student with the ball asks a question and then tosses the ball to someone to answer. If a student does not know the answer, s/he tosses the ball onward until someone gets it. The person who gets the answer correct gets to start the next question. Review the answers at the end and have the students write down the correct answers on their worksheets.

Activity Extensions

Have the students build models using materials other than marshmallows and pasta, such as toothpicks, gumdrops, caramels, Popsicle sticks, etc. Which materials made even better buildings than spaghetti and marshmallows, and why? Have the students discuss these materials in terms of compression and tension.

Give each material a cost and give groups a budget (i.e. spaghetti noodle $0.10 and marshmallows $0.20 with a $10.00 budget). Let groups pick how much of each material they want with the given budget and create a structure.

Have the students design their own experiment to look at the geometry behind different structures. Which shape can hold the most weight — a triangle, square or circle? Challenge the students to explain their answers by creating diagrams showing the compression and tension forces on each shape.

Contributors

Chris Yakacki; Ben Heavner; Malinda Schaefer Zarske; Denise Carlson

Copyright

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.